The present invention relates to an in-mold decorating method and an in-mold system in which in-mold foil including a layer having a printed design such as a color and a pattern and a base film having the layer thereon is attached into a cavity, and then molten resin is injected onto the adhesive surface of the in-mold foil to form a molded article in the cavity while joining the in-mold foil to the surface of the molded article. Hereinafter, a layer having a printed design such as a color and a pattern will be called a pattern layer, and in-mold foil will be called foil.
In a typical in-mold system, a mold is opened to peel off foil joined to the surface of a molded article while leaving a pattern layer remaining on the surface of the molded article. For example, see Japanese Patent Laid-Open No. 1-241416. FIG. 24 shows a typical in-mold system for forming a case molded article. The case molded article is a box having a specific opened face.
As shown in FIG. 24, the typical in-mold system for forming the case molded article includes a movable-side die plate 241, a fixed-side die plate 242, a foil feeder 243, and a foil winder 245. The foil feeder 243 and the foil winder 245 are both attached to the movable-side die plate 241. Long foil 244 for providing a pattern layer on the outer surface of the case molded article is drawn from the foil feeder 243. The foil 244 drawn from the foil feeder 243 is fed between the movable-side die plate 241 and the fixed-side die plate 242 and is hung over the foil winder 245. The foil feeder 243 and the foil winder 245 are rotated to feed the foil 244 from the foil feeder 243 to the foil winder 245.
When the movable-side die plate 241 and the fixed-side die plate 242 are closed, an in-mold decoration die including the movable-side die plate 241 and the fixed-side die plate 242 forms a cavity. The cavity is composed of the dented cavity-forming surface of the movable-side die plate 241 and the convex cavity-forming surface of the fixed-side die plate 242. The dented cavity-forming surface of the movable-side die plate 241 is formed on a mold movable-side nest 246 disposed on the movable-side die plate 241 while the convex cavity-forming surface of the fixed-side die plate 242 is formed on a mold fixed-side nest 247 disposed on the fixed-side die plate 242. The mold movable-side nest 246 is disposed with the dented cavity-forming surface opened to the fixed-side die plate 242 while the mold fixed-side nest 247 is disposed with the convex cavity-forming surface opposed to the dented cavity-forming surface of the mold movable-side nest 246.
The dented cavity-forming surface of the mold movable-side nest 246 is shaped depending on the outside shape of the case molded article (not shown) while the convex cavity-forming surface of the mold fixed-side nest 247 is shaped depending on the interior shape of the case molded article (not shown).
An in-mold decoration process using the typical in-mold system in FIG. 24 will be described below.
In the typical in-mold decoration process, the foil 244 is first drawn from the foil feeder 243 and is fed to the foil winder 245 while the movable-side die plate 241 and the fixed-side die plate 242 are opened. Thus, a design provided on the foil 244 is stopped at a predetermined position between the movable-side die plate 241 and the fixed-side die plate 242.
Subsequently, an ejecting mechanism (not shown) of a molder provided in the in-mold system moves a foil retaining plate 248 to a die-plate divided surface 249 of the movable-side die plate 241. Thus, the foil 244 is pressed and fixed to the die-plate divided surface 249.
The foil 244 is then stretched into the dented cavity-forming surface of the movable-side die plate 241 by, for example, vacuum suction so as to extend along the dented cavity-forming surface. The movable-side die plate 241 and the fixed-side die plate 242 are then closed to form the cavity having the dented cavity-forming surface of the movable-side die plate 241 and the convex cavity-forming surface of the fixed-side die plate 242. The cavity is a molding space shaped depending on the product shape of the manufactured case molded article.
Subsequently, the molder (not shown) injects molten resin (not shown) into the cavity so as to fill the cavity with the molten resin. When the molten resin flows into the cavity, the heat of the molten resin melts the adhesive layer of the foil 244 in the cavity, bonding the foil 244 to the molten resin.
After the completion of injection of the molten resin, the resin in the cavity is cooled by a cooling process. This solidifies the resin so as to form the case molded article (not shown). At this point, the foil 244 in the cavity is joined to the outer surface of the case molded article. The cooled resin shrinks so as to fit onto the convex cavity-forming surface of the fixed-side die plate 242. Thus, the case molded article is bonded to the convex cavity-forming surface of the fixed-side die plate 242.
Subsequently, the movable-side die plate 241 and the fixed-side die plate 242 are opened while the foil retaining plate 248 fixes the foil 244 on the die-plate divided surface 249 on the movable side. At this point, the case molded article is bonded on the convex cavity-forming surface of the fixed-side die plate 242, and thus the foil 244 joined to the case molded article is released from the movable-side die plate 241 along with the case molded article. The foil 244 includes a base film and a pattern layer stacked on a release layer disposed on the base film. With this configuration, only the pattern layer on the outer surface of the case molded article is peeled off from the release layer so as to remain on the outer surface of the case molded article. Thus, when the in-mold decoration die is opened, the pattern layer bonded to the outer surface of the case molded article is quickly peeled off from the release layer. The pattern layer not bonded to the case molded article remains on the foil 244.
In the case of subsequent molding, the foil feeder 243 and the foil winder 245 are rotated to feed a subsequent design on the foil 244 to the predetermined position between the movable-side die plate 241 and the fixed-side die plate 242. Thus, the in-mold system is prepared for the subsequent molding.